1. Field of the Invention
Embodiments of the invention described herein pertain to the field of video data. More particularly, but not by way of limitation, one or more embodiments of the invention enable systems and methods for content-protecting video codecs.
2. Description of the Related Art
Security provisions are important when providing, encoding, and decoding video data for display. Although security provisions are not usually considered part of a video codec, they can be essential to codec operation. For example, security may be desirable to the video content provider to prevent copyright infringement. Video content owners are chronic victims of illegal video capture and knock-offs.
Furthermore, the codec provider may want to protect codec software from capture, reverse engineering, or to compromise other security features, such as features designed to prevent copyright infringement.
In the video encoding and decoding process, several vulnerabilities exist that require systems and methods for implementing codec security. The system is typically susceptible to security issues whenever data is accessible to a third party, such as during transmission to the video encoder, between the encoder and media device, on the media device, between the media device and the video decoder, during transmission between the video encoder and the video decoder, and between the video decoder and the display.
Some potential vulnerabilities can be reduced or eliminated, depending on the security of various components of the transmission medium. For example, there would be no risk of security issues between the video encoder and the media device if the transfer occurred in a secured environment. Other methods may reduce the security risk during transmission between the video encoder and the video decoder, such as when the output of an Earth-based encoder is uplinked to a satellite using a highly directional antenna.
For the most part, however, risk reduction requires some form of password protection, encryption, or the like. The nature of digital video can complicate some protection mechanisms and simplify others. Consider the problem of protecting video content streaming on the Internet. If the video data is encrypted, it can be streamed, collected, re-streamed, etc., in the clear and without security concerns. However, such encryption poses various problems.
First, encryption significantly multiplies the amount of data that must be streamed. Second, decryption, which must occur before decoding, can add an intolerable processing burden, making 24 fps video display impossible. Suppose we wish to stream an encoded high definition video across the Internet to the user's computer, which is running decoder software. Bandwidth critically limits the amount of data that can be streamed per unit time—that is, the video data rate. HD data rates must be reduced if necessary to satisfy such bandwidth constraints. H.264 and HEVC codecs can do this, but reduction of data rate translates to reduction of visual quality. If e is the encryption efficiency, where n/e bits of data are required to encrypt n bits of unencrypted data, then available bandwidth has been reduced by a factor of 1/e, and video quality must suffer accordingly.
Second, decryption is a processing-intensive operation. Unless it is implemented in hardware (that is, there is a box or special purpose chip), decryption competes with the decoder for processing resources. Software decryption is well known for introducing latency. Such latency is tolerable for small jobs, but a video stream with accumulating latency is clearly unacceptable for video presentation. In short, the computational ‘stress’ of dealing with both decryption and decoding may make the whole process unworkable.
To overcome the problems and limitations described above there is a need for systems and methods for protecting video content.